Axially split casings are used in, e.g., turbo machines when a complete rotor is to be inserted into the casing. The two casing halves are connected according to the state of the art with bolts via parting line flanges arranged at the split line and are sealed to the outside as a result.
The casing is, in general, subject to stresses due to internal pressure and internal temperature, which may lead in borderline cases to deformations of the casing, associated with gaping of the split line, especially on the end faces of the casing in the area of the shaft seals. Because of limited space, the split line bolts cannot be arranged there close enough to the shaft seal to bring about a sufficient sealing effect between the casing flanges and, in the case of a axially split shaft seal, also on its joint faces.